There's a type of license eg a PPL, CPL, ATPL, IR etc. and then there are the countries from which they are issued. Yours is a Canadian PPL or CPL whichever. If you wanted to fly in another country you would require the equivelent license (PPL/CPL) but to have one issued by that particular country. In Europe, things are simplified a little by having a common license accepted in several countries. This is where your getting the term JAR from.
This link to the JAA website should explain it all
http://www.jaa.nl/licensing/licensing_overview.html
Again, regarding working for air taxi companys, it really depends on which country your applying to, each have different criteria as to the level of experience they require to allow you to fly for them.
Hope this helps,
S.C.